Fundamental rate-loss trade-off for the quantum internet

Abstract

© The Author(s) 2016. The quantum internet holds promise for achieving quantum communication - such as quantum teleportation and quantum key distribution (QKD) - freely between any clients all over the globe, as well as for the simulation of the evolution of quantum many-body systems. The most primitive function of the quantum internet is to provide quantum entanglement or a secret key to two points efficiently, by using intermediate nodes connected by optical channels with each other. Here we derive a fundamental rate-loss trade-off for a quantum internet protocol, by generalizing the Takeoka-Guha-Wilde bound to be applicable to any network topology. This trade-off has essentially no scaling gap with the quantum communication efficiencies of protocols known to be indispensable to long-distance quantum communication, such as intercity QKD and quantum repeaters. Our result - putting a practical but general limitation on the quantum internet - enables us to grasp the potential of the future quantum internet.